$9bcd - c + 8d - 2 = -3c + 9d - 10$ Solve for $b$.
Solution: Combine constant terms on the right. $9bcd - c + 8d - {2} = -3c + 9d - {10}$ $9bcd - c + 8d = -3c + 9d - {8}$ Combine $d$ terms on the right. $9bcd - c + {8d} = -3c + {9d} - 8$ $9bcd - c = -3c + {d} - 8$ Combine $c$ terms on the right. $9bcd - {c} = -{3c} + d - 8$ $9bcd = -{2c} + d - 8$ Isolate $b$ ${9}b{cd} = -2c + d - 8$ $b = \dfrac{ -2c + d - 8 }{ {9cd} }$